Comparing UWA lens of M4/3 with standard lens of FF

PakkyT

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m43 f/4 lens has the "equivalent" dof of an f/8 "full-frame" lens
Maybe nit picking but more properly that should read "m43 f/4 lens on m43 body has the "equivalent" dof of an f/8 "full-frame" lens on a FF body, when the scene is shot at the same magnification" meaning what you frame your subject the same in each system. This is key because what changes the DoF is not the lens itself nor the sensor itself, it is using the same framing causing you to either change your focal length or change your distance from camera to subject for one of the systems and that FL or distance change is what actually changes the DoF.
 
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But if I think of landscapes with m4/3 lens at f/4, be able to compensate with longer exposure?
@Lupin was referring only to depth-of-field effects.

ƒ/4 is ƒ/4, and it gathers the same amount of light per unit of area, no matter what the format is.

For some crazy reason, some people have convinced themselves that the exposure is actually different, depending on the size of the sensor. Such folks have never been able to direct me to a convincing reference — or any reference, for that matter.

Think of rain. You've got a carrot bed that is 1 metre wide by 4 metres long. Your neighbour grows 10 hectares of carrots. When it rains, your neighbour gets a lot more water over his 10 hectare field, but you both get the same amount of water per carrot!

Same with photons. True, your Fool Frame neighbour gets a total of more photons on his field, but you both get the same number of photons per unit area, assuming you're both using the same ƒ-stop. So you don't need a longer exposure to get a "proper" exposure.
 
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Lupin 3rd

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Low light seems like a huge difference, which is understood due to the large sensor. But if I think of landscapes with m4/3 lens at f/4, be able to compensate with longer exposure? I m trying to understand if it would make a really big difference in choosing one versus another?
Sometimes long exposure will work for you, sometimes it will not. EG: I was taking a long exposure of a waterfall, but then a stork decided to sit in the tree above the waterfall. The water blurred pretty nicely, but the stork turned into a grayish blob in the tree... no more long exposure... :biggrin:
 

RAH

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I do have the option to buy Z6+kit lens. But I want to understand, if I buy 7-14mm f/4 [14-28mm f/8] for my E-M1, will it not beat 24-70mm in covering scene in single frame? Some post says that it will cover but it will be different to our eyes. What does it mean?
As @Lupin 3rd says, it should be "7-14mm f/4 [14-28mm f/4]. The crop factor does not affect the light-gathering of the lens, as far as I know.

Edit: Sorry @Bytesmiths , I see that you posted a similar thought (and better written too), but yup, I agree. This is the curse of Tony Northrup rearing its ugly head (fixation on DOF and ignoring the exposure, which is MUCH more important, IMHO).
 

Clint

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Forget the equivalency thing. It is really only valid for a broad base comparison to 35mm format when first getting the lens. And even then, it just a rule of thumb, inaccurate. Just get one that meets your needs and start using it!

For 95% of camera lenses you get what you pay for. With the advent of most photos being only published on the web or computers, even some of what are considered the poorer lenes of today provide extremely nice photos for the size of the output. Expensive lenses are over rated, unless you need the durability of the lens or are that strapped for light and need a large f-stop.
 
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